This disclosure relates to dispersion-strengthened superalloys.
Conventional superalloys are known and used in high temperature applications, such as for aerospace applications. Typically, superalloys exhibit high strength from precipitation hardening or solid solution strengthening. However, a drawback of these conventional alloys is that the strength rapidly declines at temperatures above about 1300° F. (704° C.) because of thermal instability of the microstructure, which may be undesirable in many aerospace applications where there is exposure to higher temperatures.
More recently, another method of treating a superalloy has been employed to provide a more stable microstructure that facilitates maintaining a greater degree of strength above 1300° F. This method includes gas nitriding a relatively thin sheet of the superalloy to incorporate nitrogen into the microstructure and ultimately form nitrides that increase strength. The nitrides are thermally stable above 1300° F. However, a drawback of gas nitriding is that this method is limited to relatively thin sheets because incorporating the nitrogen into the superalloy relies on diffusion of nitrogen through the superalloy. Even a relatively thin superalloy sheet having a thickness under two millimeters may require a processing time of 48 hours or more to incorporate a desired amount of nitrogen. Therefore, gas nitriding is not economic or suitable for thick, three-dimensional parts.